General Structure and Function of the Digestive System

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Do Now

Why does food have to be digested before cells

can use it?

What are the typical four layers of the digestive

tract wall?

What is the name of the large serous

membrane that lines the abdominopelvic cavity

and covers the organs it contains?

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General Structure and Function

of the Digestive System

Pop Quiz

Which of the following is the correct order from the outermost to innermost layer?

A) Submucosa, serous membrane, smooth muscle, mucous membrane

B) Smooth muscle, serous membrane, mucous membrane, submucosa

C) Serous membrane, smooth muscle, submucosa, mucosa

D) Mucous membrane, submucosa, smooth muscle, serous membrane

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Pop Quiz Answer

Which of the following is the correct order from the outermost to innermost layer?

A) Submucosa, serous membrane, smooth muscle, mucous membrane

B) Smooth muscle, serous membrane, mucous membrane, submucosa

C) Serous membrane, smooth muscle, submucosa, mucosa

D) Mucous membrane, submucosa, smooth muscle, serous membrane

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Organs

of the Digestive Tract

Learning Outcomes

4. Name and locate the different

types of teeth.

5. Name and describe the functions

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• Mouth • Pharynx • Esophagus • Stomach • Small intestine • Large intestine

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Figure 19-3

The digestive system.

Which accessory organs of digestion secrete into the mouth?

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The Mouth

• Also called oral cavity, processes food by

– Ingestion

– Mastication

– Mixing with saliva

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The Teeth • Types of teeth – Incisors – Cuspids – Premolars – Molars • Sets of teeth – Deciduous – Permanent

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Figure 19-5

A molar tooth.

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The Pharynx

• Also called the throat

• Divisions

– Oropharynx

– Nasopharynx

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Organs of the Digestive Tract

The Esophagus

• Muscular tube

• No digestion occurs here

• Passes through esophageal hiatus of diaphragm to join stomach

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The Stomach • Structure – Fundus – Body – Pylorus – Sphincters • Esophageal • Pyloric – Rugae

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Figure 19-6

Longitudinal section of the stomach.

Which additional muscle layer is in the wall of the stomach that is not found in the rest of the digestive tract?

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The Stomach

• Functions

– Storage of food

– Secretion of gastric juice

• Hydrochloric acid prepares proteins for digestion

• Pepsin digests proteins

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Organs of the Digestive Tract

The Small Intestine

• Divisions

– Duodenum

– Jejunum

– Ileum

• Functions

– Enzymatic digestion of proteins and carbohydrates

– Absorption of nutrients

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Organs of the Digestive Tract

The Small Intestine

• Role of villi in small intestine

– Structure

• Microvilli

– Function

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Divisions of the Large Intestine • Cecum – Ileocecal valve – Appendix • Ascending colon • Transverse colon • Descending colon • Sigmoid colon • Rectum

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Organs of the Digestive Tract

Functions of the Large Intestine

• Secrete mucus

• Reabsorb some water

• Form feces (stool)

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How many baby teeth are there and what is the scientific name for the baby teeth?

What type of food is digested in the stomach?

What are the three divisions of the small intestine? How does the small intestine function in the

digestive process?

What are the divisions of the large intestine? What are the functions of the large intestine?

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Organs of the Digestive Tract

Pop Quiz

19.2 Which organ receives food flowing through the pyloric sphincter?

A) Stomach

B) Jejunum

C) Duodenum

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Pop Quiz Answer

19.2 Which organ receives food flowing through the pyloric sphincter?

A) Stomach

B) Jejunum

C) Duodenum D) Esophagus